1. The Alan Turing Institute , British Library, 96 Euston Road, London NW1 2DB, United Kingdom
2. Department of Statistics, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL , United Kingdom
3. Department of Statistical Science, University College, Gower Street, London WC1E 6BT, United Kingdom
4. Department of Statistics, Athens University of Economics and Business, 76 Patission Str., Athens 10434, Greece